DEAR MISS MANNERS: My friend has stated that saying “thank you” for gifts and men removing their caps in restaurants were both generational rules that are now outdated. (We are both in our 80s.)

She said we should no longer expect a thank-you for gifts, because that means the giver is giving conditionally. Her grandchildren have been advised by their mother (my friend’s daughter-in-law) that saying “thank you” for gifts is no longer necessary. Is this the trend now?

GENTLE READER: Oh, your poor friend. She is suffering from the etiquette equivalent of Stockholm syndrome.

When etiquette evolves, it is not at the direction of those who rudely violate its principles. That would be like allowing felons to revise our laws.

But as Miss Manners is the one in charge of authorizing change, she will explain to you why the examples your friend mentions are not legitimate.

Some etiquette rules have a moral basis. Gratitude, which is also an essential requirement in many religions, is permanently and inextricably linked to generosity. Those whose generosity is ignored are justified in concluding that it has not achieved its purpose of pleasing. And those who are unwilling to express gratitude should not accept favors, presents or other forms of kindness.

Other etiquette rules are merely symbolic, and therefore arbitrary and subject to change. The symbolism of hats has been in a state of confusion for some time. The traditional rule is that gentlemen remove their hats indoors as a sign of respect -- especially in a church, for example. But the arbitrariness of this is shown by the fact that piety in a synagogue is demonstrated by their wearing hats.

The traditional rule about ladies’ hats is that these did not need to be removed indoors, and wearing a head covering was even required by some churches. But then, most ladies abandoned feminine hats entirely, and many have started wearing baseball caps, which are unisex and therefore not subject to the female rule.

So in theory, the rule about gentlemen’s hats could change. But this has not yet been fully accepted. Your friend, or her masculine friends, should be aware that there are still people who are offended by seeing caps worn indoors. And while some of them are also elderly, American tourists abroad have been scorned, even by the young, for the perceived disrespect of keeping their caps on indoors, especially in churches.